package com.hmdp.utils;

import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;

/**
 * 全局ID生成器
 */
@Component
public class RedisWorker {

    private static final long BEGIN_TIMESTAMP = 1640995200L;
    private static final int COUNT_BITS = 32;

    private StringRedisTemplate stringRedisTemplate;

    public RedisWorker(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    public long nextId(String keyPrefix) {
        // 符号位 0 为正数
        // 1. 时间戳（31 bit）
        LocalDateTime now = LocalDateTime.now();
        long nowSecond = now.toEpochSecond(ZoneOffset.UTC);
        long timestamp = nowSecond - BEGIN_TIMESTAMP;
        // 2. 序列号（32 bit）
        // 2.1 获取当前日期，精确到天
        String date = now.format(DateTimeFormatter.ofPattern("yyyy:MM:dd"));
        // 2.2 自增长
        long count = stringRedisTemplate.opsForValue()
                .increment("icr:" + keyPrefix + ":" + date);
        // 3. 拼接并返回（借用位运算）
        return timestamp << COUNT_BITS | count;
    }
}
